Refactor the streaming compression code.

This patch refactors our streaming compression code to allow us to
extend it with non-zlib/non-gzip based compression schemas.

See https://bugs.torproject.org/21663

src/common/torgzip.c

@@ -399,9 +399,9 @@ detect_compression_method(const char *in, size_t in_len)
   }
 }
 
-/** Internal state for an incremental zlib compression/decompression.  The
- * body of this struct is not exposed. */
-struct tor_zlib_state_t {
+/** Internal state for an incremental compression/decompression.  The body of
+ * this struct is not exposed. */
+struct tor_compress_state_t {
   struct z_stream_s stream; /**< The zlib stream */
   int compress; /**< True if we are compressing; false if we are inflating */
 
@@ -414,14 +414,13 @@ struct tor_zlib_state_t {
   size_t allocation;
 };
 
-/** Construct and return a tor_zlib_state_t object using <b>method</b>.  If
- * <b>compress</b>, it's for compression; otherwise it's for
- * decompression. */
-tor_zlib_state_t *
-tor_zlib_new(int compress_, compress_method_t method,
-             compression_level_t compression_level)
+/** Construct and return a tor_compress_state_t object using <b>method</b>.  If
+ * <b>compress</b>, it's for compression; otherwise it's for decompression. */
+tor_compress_state_t *
+tor_compress_new(int compress_, compress_method_t method,
+                 compression_level_t compression_level)
 {
-  tor_zlib_state_t *out;
+  tor_compress_state_t *out;
   int bits, memlevel;
 
  if (! compress_) {
@@ -430,7 +429,7 @@ tor_zlib_new(int compress_, compress_method_t method,
    compression_level = HIGH_COMPRESSION;
  }
 
- out = tor_malloc_zero(sizeof(tor_zlib_state_t));
+ out = tor_malloc_zero(sizeof(tor_compress_state_t));
  out->stream.zalloc = Z_NULL;
  out->stream.zfree = Z_NULL;
  out->stream.opaque = NULL;
@@ -462,16 +461,17 @@ tor_zlib_new(int compress_, compress_method_t method,
  * to *<b>out</b>, adjusting the values as we go.  If <b>finish</b> is true,
  * we've reached the end of the input.
  *
- * Return TOR_ZLIB_DONE if we've finished the entire compression/decompression.
- * Return TOR_ZLIB_OK if we're processed everything from the input.
- * Return TOR_ZLIB_BUF_FULL if we're out of space on <b>out</b>.
- * Return TOR_ZLIB_ERR if the stream is corrupt.
+ * Return TOR_COMPRESS_DONE if we've finished the entire
+ * compression/decompression.
+ * Return TOR_COMPRESS_OK if we're processed everything from the input.
+ * Return TOR_COMPRESS_BUFFER_FULL if we're out of space on <b>out</b>.
+ * Return TOR_COMPRESS_ERROR if the stream is corrupt.
  */
-tor_zlib_output_t
-tor_zlib_process(tor_zlib_state_t *state,
-                 char **out, size_t *out_len,
-                 const char **in, size_t *in_len,
-                 int finish)
+tor_compress_output_t
+tor_compress_process(tor_compress_state_t *state,
+                     char **out, size_t *out_len,
+                     const char **in, size_t *in_len,
+                     int finish)
 {
   int err;
   tor_assert(*in_len <= UINT_MAX);
@@ -498,31 +498,31 @@ tor_zlib_process(tor_zlib_state_t *state,
   if (! state->compress &&
       is_compression_bomb(state->input_so_far, state->output_so_far)) {
     log_warn(LD_DIR, "Possible zlib bomb; abandoning stream.");
-    return TOR_ZLIB_ERR;
+    return TOR_COMPRESS_ERROR;
   }
 
   switch (err)
     {
     case Z_STREAM_END:
-      return TOR_ZLIB_DONE;
+      return TOR_COMPRESS_DONE;
     case Z_BUF_ERROR:
       if (state->stream.avail_in == 0 && !finish)
-        return TOR_ZLIB_OK;
-      return TOR_ZLIB_BUF_FULL;
+        return TOR_COMPRESS_OK;
+      return TOR_COMPRESS_BUFFER_FULL;
     case Z_OK:
       if (state->stream.avail_out == 0 || finish)
-        return TOR_ZLIB_BUF_FULL;
-      return TOR_ZLIB_OK;
+        return TOR_COMPRESS_BUFFER_FULL;
+      return TOR_COMPRESS_OK;
     default:
       log_warn(LD_GENERAL, "Gzip returned an error: %s",
                state->stream.msg ? state->stream.msg : "<no message>");
-      return TOR_ZLIB_ERR;
+      return TOR_COMPRESS_ERROR;
     }
 }
 
 /** Deallocate <b>state</b>. */
 void
-tor_zlib_free(tor_zlib_state_t *state)
+tor_compress_free(tor_compress_state_t *state)
 {
   if (!state)
     return;
@@ -553,7 +553,7 @@ tor_zlib_state_size_precalc(int inflate_, int windowbits, int memlevel)
        that is, 32K for windowBits=15 (default value) plus a few kilobytes
        for small objects."
     */
-    return sizeof(tor_zlib_state_t) + sizeof(struct z_stream_s) +
+    return sizeof(tor_compress_state_t) + sizeof(struct z_stream_s) +
       (1 << 15) + A_FEW_KILOBYTES;
   } else {
     /* Also from zconf.h:
@@ -562,7 +562,7 @@ tor_zlib_state_size_precalc(int inflate_, int windowbits, int memlevel)
             (1 << (windowBits+2)) +  (1 << (memLevel+9))
         ... plus a few kilobytes for small objects."
     */
-    return sizeof(tor_zlib_state_t) + sizeof(struct z_stream_s) +
+    return sizeof(tor_compress_state_t) + sizeof(struct z_stream_s) +
       (1 << (windowbits + 2)) + (1 << (memlevel + 9)) + A_FEW_KILOBYTES;
   }
 #undef A_FEW_KILOBYTES
@@ -570,7 +570,7 @@ tor_zlib_state_size_precalc(int inflate_, int windowbits, int memlevel)
 
 /** Return the approximate number of bytes allocated for <b>state</b>. */
 size_t
-tor_zlib_state_size(const tor_zlib_state_t *state)
+tor_compress_state_size(const tor_compress_state_t *state)
 {
   return state->allocation;
 }

src/common/torgzip.h

@@ -46,23 +46,27 @@ tor_zlib_get_header_version_str(void);
 
 compress_method_t detect_compression_method(const char *in, size_t in_len);
 
-/** Return values from tor_zlib_process; see that function's documentation for
- * details. */
+/** Return values from tor_compress_process; see that function's documentation
+ * for details. */
 typedef enum {
-  TOR_ZLIB_OK, TOR_ZLIB_DONE, TOR_ZLIB_BUF_FULL, TOR_ZLIB_ERR
-} tor_zlib_output_t;
+  TOR_COMPRESS_OK,
+  TOR_COMPRESS_DONE,
+  TOR_COMPRESS_BUFFER_FULL,
+  TOR_COMPRESS_ERROR
+} tor_compress_output_t;
 /** Internal state for an incremental zlib compression/decompression. */
-typedef struct tor_zlib_state_t tor_zlib_state_t;
-tor_zlib_state_t *tor_zlib_new(int compress, compress_method_t method,
-                               compression_level_t level);
+typedef struct tor_compress_state_t tor_compress_state_t;
+tor_compress_state_t *tor_compress_new(int compress,
+                                       compress_method_t method,
+                                       compression_level_t level);
 
-tor_zlib_output_t tor_zlib_process(tor_zlib_state_t *state,
-                                   char **out, size_t *out_len,
-                                   const char **in, size_t *in_len,
-                                   int finish);
-void tor_zlib_free(tor_zlib_state_t *state);
+tor_compress_output_t tor_compress_process(tor_compress_state_t *state,
+                                           char **out, size_t *out_len,
+                                           const char **in, size_t *in_len,
+                                           int finish);
+void tor_compress_free(tor_compress_state_t *state);
 
-size_t tor_zlib_state_size(const tor_zlib_state_t *state);
+size_t tor_compress_state_size(const tor_compress_state_t *state);
 size_t tor_zlib_get_total_allocation(void);
 
 #endif

src/or/buffers.c

@@ -2088,11 +2088,11 @@ fetch_from_buf_line(buf_t *buf, char *data_out, size_t *data_len)
 }
 
 /** Compress on uncompress the <b>data_len</b> bytes in <b>data</b> using the
- * zlib state <b>state</b>, appending the result to <b>buf</b>.  If
+ * compression state <b>state</b>, appending the result to <b>buf</b>.  If
  * <b>done</b> is true, flush the data in the state and finish the
  * compression/uncompression.  Return -1 on failure, 0 on success. */
 int
-write_to_buf_zlib(buf_t *buf, tor_zlib_state_t *state,
+write_to_buf_zlib(buf_t *buf, tor_compress_state_t *state,
                   const char *data, size_t data_len,
                   int done)
 {
@@ -2108,20 +2108,22 @@ write_to_buf_zlib(buf_t *buf, tor_zlib_state_t *state,
     }
     next = CHUNK_WRITE_PTR(buf->tail);
     avail = old_avail = CHUNK_REMAINING_CAPACITY(buf->tail);
-    switch (tor_zlib_process(state, &next, &avail, &data, &data_len, done)) {
-      case TOR_ZLIB_DONE:
+    switch (tor_compress_process(state, &next, &avail,
+                                 &data, &data_len, done)) {
+      case TOR_COMPRESS_DONE:
         over = 1;
         break;
-      case TOR_ZLIB_ERR:
+      case TOR_COMPRESS_ERROR:
         return -1;
-      case TOR_ZLIB_OK:
+      case TOR_COMPRESS_OK:
         if (data_len == 0)
           over = 1;
         break;
-      case TOR_ZLIB_BUF_FULL:
+      case TOR_COMPRESS_BUFFER_FULL:
         if (avail) {
-          /* Zlib says we need more room (ZLIB_BUF_FULL).  Start a new chunk
-           * automatically, whether were going to or not. */
+          /* The compression module says we need more room
+           * (TOR_COMPRESS_BUFFER_FULL).  Start a new chunk automatically,
+           * whether were going to or not. */
           need_new_chunk = 1;
         }
         break;

src/or/buffers.h

@@ -36,7 +36,7 @@ int flush_buf(tor_socket_t s, buf_t *buf, size_t sz, size_t *buf_flushlen);
 int flush_buf_tls(tor_tls_t *tls, buf_t *buf, size_t sz, size_t *buf_flushlen);
 
 int write_to_buf(const char *string, size_t string_len, buf_t *buf);
-int write_to_buf_zlib(buf_t *buf, tor_zlib_state_t *state,
+int write_to_buf_zlib(buf_t *buf, tor_compress_state_t *state,
                       const char *data, size_t data_len, int done);
 int move_buf_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen);
 int fetch_from_buf(char *string, size_t string_len, buf_t *buf);

src/or/circuitlist.c

@@ -1991,8 +1991,8 @@ single_conn_free_bytes(connection_t *conn)
   if (conn->type == CONN_TYPE_DIR) {
     dir_connection_t *dir_conn = TO_DIR_CONN(conn);
     if (dir_conn->zlib_state) {
-      result += tor_zlib_state_size(dir_conn->zlib_state);
-      tor_zlib_free(dir_conn->zlib_state);
+      result += tor_compress_state_size(dir_conn->zlib_state);
+      tor_compress_free(dir_conn->zlib_state);
       dir_conn->zlib_state = NULL;
     }
   }

src/or/connection.c

@@ -628,7 +628,7 @@ connection_free_(connection_t *conn)
     dir_connection_t *dir_conn = TO_DIR_CONN(conn);
     tor_free(dir_conn->requested_resource);
 
-    tor_zlib_free(dir_conn->zlib_state);
+    tor_compress_free(dir_conn->zlib_state);
     if (dir_conn->spool) {
       SMARTLIST_FOREACH(dir_conn->spool, spooled_resource_t *, spooled,
                         spooled_resource_free(spooled));

src/or/directory.c

@@ -3178,7 +3178,7 @@ handle_get_current_consensus(dir_connection_t *conn,
     write_http_response_header(conn, -1, compressed,
                                smartlist_len(conn->spool) == 1 ? lifetime : 0);
     if (! compressed)
-      conn->zlib_state = tor_zlib_new(0, ZLIB_METHOD, HIGH_COMPRESSION);
+      conn->zlib_state = tor_compress_new(0, ZLIB_METHOD, HIGH_COMPRESSION);
 
     /* Prime the connection with some data. */
     const int initial_flush_result = connection_dirserv_flushed_some(conn);
@@ -3276,8 +3276,8 @@ handle_get_status_vote(dir_connection_t *conn, const get_handler_args_t *args)
 
     if (smartlist_len(items)) {
       if (compressed) {
-        conn->zlib_state = tor_zlib_new(1, ZLIB_METHOD,
-                                    choose_compression_level(estimated_len));
+        conn->zlib_state = tor_compress_new(1, ZLIB_METHOD,
+                           choose_compression_level(estimated_len));
         SMARTLIST_FOREACH(items, const char *, c,
                  connection_write_to_buf_zlib(c, strlen(c), conn, 0));
         connection_write_to_buf_zlib("", 0, conn, 1);
@@ -3335,7 +3335,7 @@ handle_get_microdesc(dir_connection_t *conn, const get_handler_args_t *args)
     write_http_response_header(conn, -1, compressed, MICRODESC_CACHE_LIFETIME);
 
     if (compressed)
-      conn->zlib_state = tor_zlib_new(1, ZLIB_METHOD,
+      conn->zlib_state = tor_compress_new(1, ZLIB_METHOD,
                                       choose_compression_level(size_guess));
 
     const int initial_flush_result = connection_dirserv_flushed_some(conn);
@@ -3428,7 +3428,7 @@ handle_get_descriptor(dir_connection_t *conn, const get_handler_args_t *args)
       }
       write_http_response_header(conn, -1, compressed, cache_lifetime);
       if (compressed)
-        conn->zlib_state = tor_zlib_new(1, ZLIB_METHOD,
+        conn->zlib_state = tor_compress_new(1, ZLIB_METHOD,
                                         choose_compression_level(size_guess));
       clear_spool = 0;
       /* Prime the connection with some data. */
@@ -3519,8 +3519,8 @@ handle_get_keys(dir_connection_t *conn, const get_handler_args_t *args)
 
     write_http_response_header(conn, compressed?-1:len, compressed, 60*60);
     if (compressed) {
-      conn->zlib_state = tor_zlib_new(1, ZLIB_METHOD,
-                                      choose_compression_level(len));
+      conn->zlib_state = tor_compress_new(1, ZLIB_METHOD,
+                                          choose_compression_level(len));
       SMARTLIST_FOREACH(certs, authority_cert_t *, c,
             connection_write_to_buf_zlib(c->cache_info.signed_descriptor_body,
                                          c->cache_info.signed_descriptor_len,

src/or/dirserv.c

@@ -3792,7 +3792,7 @@ connection_dirserv_flushed_some(dir_connection_t *conn)
     /* Flush the zlib state: there could be more bytes pending in there, and
      * we don't want to omit bytes. */
     connection_write_to_buf_zlib("", 0, conn, 1);
-    tor_zlib_free(conn->zlib_state);
+    tor_compress_free(conn->zlib_state);
     conn->zlib_state = NULL;
   }
   return 0;

src/or/or.h

@@ -1773,8 +1773,8 @@ typedef struct dir_connection_t {
   /** List of spooled_resource_t for objects that we're spooling. We use
    * it from back to front. */
   smartlist_t *spool;
-  /** The zlib object doing on-the-fly compression for spooled data. */
-  tor_zlib_state_t *zlib_state;
+  /** The compression object doing on-the-fly compression for spooled data. */
+  tor_compress_state_t *zlib_state;
 
   /** What rendezvous service are we querying for? */
   rend_data_t *rend_data;

src/test/test_buffers.c

@@ -584,12 +584,12 @@ test_buffers_zlib_impl(int finalize_with_nil)
   char *contents = NULL;
   char *expanded = NULL;
   buf_t *buf = NULL;
-  tor_zlib_state_t *zlib_state = NULL;
+  tor_compress_state_t *zlib_state = NULL;
   size_t out_len, in_len;
   int done;
 
   buf = buf_new_with_capacity(128); /* will round up */
-  zlib_state = tor_zlib_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
+  zlib_state = tor_compress_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
 
   msg = tor_malloc(512);
   crypto_rand(msg, 512);
@@ -621,7 +621,7 @@ test_buffers_zlib_impl(int finalize_with_nil)
 
  done:
   buf_free(buf);
-  tor_zlib_free(zlib_state);
+  tor_compress_free(zlib_state);
   tor_free(contents);
   tor_free(expanded);
   tor_free(msg);
@@ -647,7 +647,7 @@ test_buffers_zlib_fin_at_chunk_end(void *arg)
   char *contents = NULL;
   char *expanded = NULL;
   buf_t *buf = NULL;
-  tor_zlib_state_t *zlib_state = NULL;
+  tor_compress_state_t *zlib_state = NULL;
   size_t out_len, in_len;
   size_t sz, headerjunk;
   (void) arg;
@@ -666,7 +666,7 @@ test_buffers_zlib_fin_at_chunk_end(void *arg)
   tt_uint_op(buf->head->datalen, OP_EQ, headerjunk);
   tt_uint_op(buf_datalen(buf), OP_EQ, headerjunk);
   /* Write an empty string, with finalization on. */
-  zlib_state = tor_zlib_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
+  zlib_state = tor_compress_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
   tt_int_op(write_to_buf_zlib(buf, zlib_state, "", 0, 1), OP_EQ, 0);
 
   in_len = buf_datalen(buf);
@@ -687,7 +687,7 @@ test_buffers_zlib_fin_at_chunk_end(void *arg)
 
  done:
   buf_free(buf);
-  tor_zlib_free(zlib_state);
+  tor_compress_free(zlib_state);
   tor_free(contents);
   tor_free(expanded);
   tor_free(msg);

src/test/test_util.c

@@ -2249,7 +2249,7 @@ test_util_gzip(void *arg)
   char *buf1=NULL, *buf2=NULL, *buf3=NULL, *cp1, *cp2;
   const char *ccp2;
   size_t len1, len2;
-  tor_zlib_state_t *state = NULL;
+  tor_compress_state_t *state = NULL;
 
   (void)arg;
   buf1 = tor_strdup("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAZAAAAAAAAAAAAAAAAAAAZ");
@@ -2320,21 +2320,21 @@ test_util_gzip(void *arg)
   tor_free(buf1);
   tor_free(buf2);
   tor_free(buf3);
-  state = tor_zlib_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
+  state = tor_compress_new(1, ZLIB_METHOD, HIGH_COMPRESSION);
   tt_assert(state);
   cp1 = buf1 = tor_malloc(1024);
   len1 = 1024;
   ccp2 = "ABCDEFGHIJABCDEFGHIJ";
   len2 = 21;
-  tt_assert(tor_zlib_process(state, &cp1, &len1, &ccp2, &len2, 0)
-              == TOR_ZLIB_OK);
+  tt_int_op(tor_compress_process(state, &cp1, &len1, &ccp2, &len2, 0),
+            OP_EQ, TOR_COMPRESS_OK);
   tt_int_op(0, OP_EQ, len2); /* Make sure we compressed it all. */
   tt_assert(cp1 > buf1);
 
   len2 = 0;
   cp2 = cp1;
-  tt_assert(tor_zlib_process(state, &cp1, &len1, &ccp2, &len2, 1)
-              == TOR_ZLIB_DONE);
+  tt_int_op(tor_compress_process(state, &cp1, &len1, &ccp2, &len2, 1),
+            OP_EQ, TOR_COMPRESS_DONE);
   tt_int_op(0, OP_EQ, len2);
   tt_assert(cp1 > cp2); /* Make sure we really added something. */
 
@@ -2346,7 +2346,7 @@ test_util_gzip(void *arg)
 
  done:
   if (state)
-    tor_zlib_free(state);
+    tor_compress_free(state);
   tor_free(buf2);
   tor_free(buf3);
   tor_free(buf1);
@@ -2364,7 +2364,7 @@ test_util_gzip_compression_bomb(void *arg)
   char *one_mb = tor_malloc_zero(one_million);
   char *result = NULL;
   size_t result_len = 0;
-  tor_zlib_state_t *state = NULL;
+  tor_compress_state_t *state = NULL;
 
   /* Make sure we can't produce a compression bomb */
   setup_full_capture_of_logs(LOG_WARN);
@@ -2386,22 +2386,22 @@ test_util_gzip_compression_bomb(void *arg)
                                       ZLIB_METHOD, 0, LOG_WARN));
 
   /* Now try streaming that. */
-  state = tor_zlib_new(0, ZLIB_METHOD, HIGH_COMPRESSION);
-  tor_zlib_output_t r;
+  state = tor_compress_new(0, ZLIB_METHOD, HIGH_COMPRESSION);
+  tor_compress_output_t r;
   const char *inp = compression_bomb;
   size_t inlen = 1039;
   do {
     char *outp = one_mb;
     size_t outleft = 4096; /* small on purpose */
-    r = tor_zlib_process(state, &outp, &outleft, &inp, &inlen, 0);
+    r = tor_compress_process(state, &outp, &outleft, &inp, &inlen, 0);
     tt_int_op(inlen, OP_NE, 0);
-  } while (r == TOR_ZLIB_BUF_FULL);
+  } while (r == TOR_COMPRESS_BUFFER_FULL);
 
-  tt_int_op(r, OP_EQ, TOR_ZLIB_ERR);
+  tt_int_op(r, OP_EQ, TOR_COMPRESS_ERROR);
 
  done:
   tor_free(one_mb);
-  tor_zlib_free(state);
+  tor_compress_free(state);
 }
 
 /** Run unit tests for mmap() wrapper functionality. */